1. Field of the Invention
The present invention relates to a magnetic recording medium having a non-magnetic base and a magnetic layer thereon containing magnetizable particles dispersed in a resinous binder in combination with a lubricant.
2. Prior Art
A magnetic recording medium, whether used for audio recording, video recording or other magnetic recording purposes comes in contact with guide members, magnetic heads and the like during use. For example, in a case of a video tape recorder, where high tape velocities are encountered, the tape must have sufficient wear resistance and a relatively small friction coefficient if it is to run smoothly and steadily for a long time. Moreover, the magnetic powder on a recording medium must be sufficiently bound thereto to resist shedding or loosening of such powder during use and in instances where the recording medium is tape, it must exhibit good splicing-ability.
Magnetic recording media which have an increased friction coefficient vibrate at the guide members and at the magnetic heads during the recording operation and/or during the reproducing operation so that the recorded signals or the reproduced signals are distorted from the original signals. In some cases, a so-called "Q" sound, due to the vibration of the magnetic recording media, is encountered.
Efforts have been made to overcome the above-described defects and to impart lubricity or smoothness to the magnetic recording media, but no completely satisfactory lubricant for magnetic recording media, has yet been developed. For example, it has been suggested to use lubricants, such as silicone fluid, castor oil, molybdenum disulfide, graphite, higher fatty acids and the like whereby the lubricant is mixed into a magnetic layer containing a magnetic powder, such as gamma ferric oxide, .alpha. -Fe.sub.2 O.sub.3, and a binder, such as polyvinyl chloride. Magnetic recording media containing such lubricants exhibit some wear resistance, but not to a sufficient degree. When a large quantity of one of the above enumerated lubricants is mixed into the magnetic layer in order to further increase the wear resistance, so-called "bleeding" or "blooming" phenomena occur on the magnetic layer. The bleeding or blooming phenomena result from the lubricating agent oozing or diffusing onto the surface of the magnetic layer and becoming separated therefrom. As a result, the surface of the magnetic recording media gets rough and more magnetic powder separates or is rubbed off from the magnetic recording layer during use. When the friction coefficient is too large, the "Q" sound cannot be avoided.
Recently, S. Higuchi et al disclosed and claimed in U.S. Pat. No. 3,993,846 a polyoxyalkylene substituted organosilicon compound having the formula: EQU RO(CHR"CH.sub.2 O).sub.n.sbsb.1 (SiCH.sub.3 CH.sub.3 O).sub.m (CH.sub.2 CHR"O).sub.n.sbsb.2 R'
wherein R and R' comprise an aliphatic hydrocarbon group having from 8 to 18 carbon atoms, R" is a hydrogen atom or a methyl group, m is an integer ranging from 1 to 15 and n.sub.1 and n.sub.2 are integers whose sums range from 2 to 16 as a lubricant for a magnetic recording medium. This lubricant exhibits considerable promise in providing an improved magnetic recording medium wherein at least some, if not all, of the aforesaid prior art problems are alleviated. S. Higuchi et al also disclosed and claimed in U.S. Pat. No. 4,007,313 a fluoro-organosilicon compound having the formula: ##STR1## wherein R is an aliphatic hydrocarbon group having from 7 to 17 carbon atoms and n is an integer ranging from 1 to 3 as a lubricant for use with the magnetic recording medium. This lubricant also exhibits considerable promise in providing an improved magnetic recording medium wherein at least some, if not all, of the aforesaid prior art problems are alleviated. S. Higuchi et al also disclosed and claimed in U.S. Pat. No 4,007,314 an organosilicon compound having the formula: EQU (RCOO).sub.n Si(CH.sub.3).sub.4-n
wherein R is an aliphatic hydrocarbon group containing from 7 to 17 carbon atoms and n is an integer ranging from 1 to 3 as a lubricant for use with a magnetic recording medium. This lubricant also exhibits considerable promise in providing an improved magnetic recording medium wherein at least some, if not all, of the aforesaid prior art problems are alleviated. While the aforesaid Higuchi et al lubricants are preferred over prior art lubricants, it is nevertheless desirable to develope yet further improved magnetic recording lubricants.